I dunno if its really a bug or if its just a problem on my side. I've got a >12 password for lastfm, and I tried to use it in vlc to scrobbling the music. But after hundreds of tests, it still said: Nopes, your password or username is incorrect....
So I tried to change the password to a shorter one...and then: It works!
So there is a limit?
If yes, I would really prefer it, to set the length on more then 32 characters....yeps, there are ppl with such a long password

greets from germany
Keenora